L-Ornithine
Commonly used for
SleepAthletic PerformanceEnergy
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What is it? / Overview
L-Ornithine participates in the urea cycle, helping remove ammonia produced during protein metabolism. Small studies suggest possible improvements in fatigue and sleep quality, but evidence remains weak and inconsistent.
How is it used? / Administration
Form: L-Ornithine hydrochloride
Typical dose studied: 2–6 g/day
Timing: Evening for sleep support, or post-exercise for recovery
Human evidence limited and based on relatively small studies. Benefits appear modest compared with established recovery supplements.
How well does it work? / Evidence
? Emerging / limited evidence
Who should avoid it?
Avoid with: End-stage liver disease / Cirrhosis
Already taking it? Reassess after several weeks due to limited evidence.
Research & references
Miyake M et al. (2014). L-ornithine, stress markers, and sleep quality RCT. Nutrition Journal. Sugino T et al. (2008). L-ornithine and physical fatigue in healthy volunteers. Nutrition Research. Wu G. (2021). Amino Acids: Biochemistry and Nutrition. CRC Press.
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